This proposal, Mechanisms of regulation by RNA in acute myeloid leukemia, is being submitted in response to PAR-14-267, Outstanding Investigator Award (R35), from the National Cancer Institute. The objective is to allow experienced investigators to conduct exceptional research and be more adventurous. In recent years researchers have revealed that a large portion of the genome of complex organisms are transcribed but not translated. These noncoding RNAs (ncRNAs) provide an additional and relatively unexplored layer of control to many biological processes. While many investigators are now turning to categorizing and studying ncRNAs, especially microRNAs, there are several areas which have not been extensively studied. (1) The first is the role of antisense RNAs in limiting the expression of tumor suppressor genes, especially those of master transcription factors. (2) In this era of sequencing total DNA genomes for the presence of mutations, especially in cancer, most investigators do not consider that there is another layer of modification of the genome, that of RNA editing, and that this has been shown to play a role in cancer. (3) Most importantly, many investigators are studying epigenetic modifications of the genome, especially DNA methylation, with the view that these control genome activity. Relatively little attention has been given to the potential role of RNA (i.e., transcription) in controlling epigenetic marks. The overall goal of this proposal is to investigate these 3 novel and underexplored aspects of RNA control in cancer, focusing on acute myeloid leukemia (AML) as a model for other tumor types. Therefore, this proposal will study the role of RNA biology in cancer, focusing in three novel areas: (1) the study of a noncoding RNA which limits expression of the tumor suppressor PU.1, and in particular investigate its role in the core binding factor leukemias. As time permits, other antisense RNAs will be identified. (2) The role of dysregulation of RNA editing in AML will be investigated, and in particular the suppression of the RNA editing enzyme ADAR2 in core binding factor leukemias, and the misexpression of ADAR3. (3) The ability of ncRNA to regulate epigenetic changes such as DNA methylation will be studied in more detail, with the goals of developing gene-selective demethylating tools as well as identification of other epigenetic marks regulated by ncRNAs. In addition to exploring novel areas of RNA biology, these studies will in every instance seek to investigate their role in cancer, as well as potential development of more specific therapeutic modalities, using AML as a model disease.